ACUTE EFFECTS OF ENDOTHALL GILL, INTESTINE AND LIVER OF ZEBRAFISH (DANIO RERIO)

Endothall (7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid) is a selective contact herbicide. In this work, it was investigated whether endothall caused histopathological alterations in various tissues of non-target zebrafish (Danio rerio). Zebrafish were exposed to 0.1mg/L, 0.5mg/L and 1mg/L endothall for five days. Gill, intestine and liver samples were removed, fixed and embedded in paraffin. Sections were stained with hematoxylin-eosin and investigated by light microscopy. In the gills, epithelial hyperplasia, desquamation, curling of secondary lamellae, hemorrhage, aneurysm, edema, epithelial lifting, apical fusion, deformation of secondary lamellae, enlargement of the central vein and necrosis were noted. Intestine tissues exhibited deformation of brush border, the separation between mucosa and lamina propria, muscle fiber detachments in muscularis, rupture of serosa epithelium, degeneration of mucosal epithelial cells, vacuolization, villus structure deformities, cytoplasmic degeneration of mucosal epithelial cells and hyperplasia. Liver samples showed sinusoidal congestion, vacuolization, degenerative hepatocytes, degenerative ducts and necrosis. Our results indicated that acute endothall exposure caused multi-organ histopathology in zebrafish.